Flexible micromachined transducer device and method for fabricating same

Abstract

Techniques and structures for providing flexibility of a micromachined transducer array. In an embodiment, a transducer array includes a plurality of transducer elements each comprising a piezoelectric element and one or more electrodes disposed in or on a support layer. The support layer is bonded to a flexible layer including a polymer material, wherein flexibility of the transducer array results in part from a total thickness of a flexible layer. In another embodiment, flexibility of the transducer array results in part from one or more flexural structures formed therein.

What is claimed is: 
     
       1. A micromachined transducer array comprising:
 a plurality of transducer elements each comprising:
 a respective electrode disposed on a first side of a support layer including a bulk semiconductor material; 
 a respective piezoelectric element disposed on the first side of the support layer; and 
 a respective interconnect in the support layer coupled to the respective electrode of the transducer element, wherein the interconnect extends through the support layer between the first side and a second side of the support layer; and 
 
 a flexible layer bonded by an adhesive material to the second side of the support layer, wherein the flexible layer includes a polymer material and, for each of the respective interconnects of the plurality of transducer elements, a corresponding interconnect extending through the flexible layer; 
 wherein the adhesive material provides at least partial electrical isolation of the respective interconnects of the plurality of transducer elements from one another; 
 wherein conductive fillers are disposed in the adhesive material; and 
 wherein the respective interconnects of the plurality of transducer elements are each electrically coupled via the conductive fillers to the corresponding interconnect extending through the flexible layer. 
 
     
     
       2. The micromachined transducer array of  claim 1 , wherein a total thickness of the support layer between the first side and the second side is equal to or less than 100 microns. 
     
     
       3. The micromachined transducer array of  claim 1 , wherein the polymer material includes polyimide. 
     
     
       4. The micromachined transducer array of  claim 1 , wherein each of the plurality of transducer elements includes:
 a reference electrode disposed on the first side of the support layer; 
 a drive/sense electrode disposed on the first side of the support layer; 
 a reference interconnect in the support layer, the reference interconnect coupled to the reference electrode of the transducer element; and 
 a drive/sense interconnect in the support layer, the drive/sense interconnect coupled to the drive/sense electrode of the transducer element. 
 
     
     
       5. The micromachined transducer array of  claim 1 , wherein the support layer further comprises a flexural structure between a first transducer element and a second transducer element. 
     
     
       6. The micromachined transducer array of  claim 5 , wherein the flexural structure separates portions of the support layer from one another. 
     
     
       7. The micromachined transducer array of  claim 1 , wherein the flexible layer is bonded to the second side of the support layer with a eutectic bond. 
     
     
       8. The micromachined transducer array of  claim 1 , wherein the flexible layer includes a first interconnect comprising a first portion to carry a signal laterally along the flexible layer. 
     
     
       9. An apparatus for generating and sensing pressure waves in a medium, the apparatus comprising:
 the micromachined transducer array of any of  claims 1 - 4  and  5 ; 
 generating means coupled to the micromachined transducer array to apply an electrical drive signal on at least one drive/sense electrode; 
 receiving means coupled to the micromachined transducer array to receive an electrical response signal from at least one drive/sense electrode; and 
 signal processing means coupled to the receiving means to process electrical response signals received from the plurality of the drive/sense electrodes. 
 
     
     
       10. The apparatus of  claim 9 , wherein the generating means is to apply an electrical drive signal to cause at least one piezoelectric element of the plurality of transducer elements to resonate at an ultrasonic frequency.